Regenerative Medicine is the process of creating living, functional tissues to repair or replace tissue or organ function lost due to damage, or congenital defects. This field holds the promise of regenerating damaged tissues and organs in the body by stimulating previously irreparable organs to heal themselves.
One method used to regenerate tissue or organ function is the delivery of stem cells to the affected organ or tissue. However, stem cells are not well retained in the organ targeted for tissue regeneration even when the stem cells are directly injected into the tissue of the injured organ. Imaging studies in humans and animals have demonstrated that most of the delivered stem ceils can be found within the spleen within an hour after stem cell injection. Animal studies have also demonstrated that surgical removal of the spleen prior to stem cell therapy after induced myocardial infarction improved functional recovery of the damaged hearts (Blood, Vol 84, No 5: 1482-1491, 1994; NATURE 410:701-705, 2001). Splenectomy has also been shown to improve engraftment in human patients after bone marrow transplantation (Stem Cells Dev 13(1):51-62, 2004; Transplant Proc. 28(2):736-7, 1996; Am J Hematol. 22(3):275-83, 1986). However, splenectomy is also associated with surgical mortality, sepsis, and lifelong thrombotic complications (Blood Rev. 14(3):121-129, 2000; Leukemia. 15(3):465-467, 2001; Pediatr Transplant 13(2):171-176, 2009)
Thus, there is a need to develop methods and compositions that can be used to prevent localization of stem cells in the spleen and other lymphoid tissues without removal of the spleen.